Silver concentration effects on structural and electrical properties of La0.4Pr0.25Ca0.35-xAgxMnO3 manganite elaborated by sol–gel method

La0.4Pr0.25Ca0.35-xAgxMnO3 samples were elaborated using sol–gel method. X-ray diffraction study indicates that the investigated compounds exhibit an orthorhombic structure with Pbnm space-group symmetry. Introducing Ag in the investigated system leads to changes in the unit cell parameters and cell volume. The electrical properties have been investigated using the impedance spectroscopy technique. Dc-electrical resistivity study shows a metal-semiconductor transition at TMS = 220 K, which is Ag independent. Also, it is found that the resistivity decreases with increasing silver content. Then, the activation energy of the hopping mechanism is reduced with increasing Ag concentration. For different silver concentration, the conduction is dominated by thermally activated small polaron hopping (SPH) process at the high temperature and by variable range hopping (VRH) process at lower temperatures.